[ClusterLabs] related to fencing in general , docker containers

[Sridhar K]

Thank you Ken,Andrei for the response

As of now, I have completed the below  (below is for POC purpose) Ideally
there will be 3 VM's and each VM will have one docker container
[pacemaker + corosync + sqlServer] same network
1.Created a docker image with [pacemaker + corosync + sqlServer]
2. Created a docker network and brought up 3 containers of the above image
which are part of the created network
3. Created  a pacemaker cluster out of 3 containers
4. Create AG group of sqlserver
5. Tested failover of Sqlserver , by making a container(i,e pcs cluster
standby container id) to standby , failover was working.

All above was in a VM , now need to think w.r.t fencing
As the pacemaker is running within the docker container anything w.r.t
fencing may not help
next was checking, how about doing something w.r.t fencing at VM level so
that fencing can kill/restart the docker container as required.

considering 3 VMs
If 1 VM itself goes down , SqlServer will be still up as two VM's are fine
and within them, docker containers (pacemaker + corosync + sqlServer) are
running
If 2 VM goes down , then SqlServer will not be available.


Related to Bundles
I tried, and got an error posted the same  in the forum, also in Bundles
required number of replicas will be spawned, How can I configure out of 3
replicas which will be my master Sqlserver and the rest will be replicas


Hi Ken,
will check this, if am able to fence docker containers(pacemaker +
corosync + sqlServer), it should be of some help, and will check how to
handle VM failures

You
> will probably need one fencing agent for each physical host where
> docker
> is running and map cluster nodes (containers) to the correct agent
> (i.e.
> physical host).

Regards
Sridhar




On Fri, 17 Jun 2022 at 20:29, Andrei Borzenkov <arvidjaar at gmail.com> wrote:

> On 17.06.2022 16:53, Sridhar K wrote:
> > Hi Team,
> >
> > Please share any pointers, references, example usage's w.r.t fencing in
> > general and its use w.r.t docker containers.
> >
> > referring as of now
> > https://clusterlabs.org/pacemaker/doc/crm_fencing.html
> >
> > need to check the feasibility of fencing w.r.t docker containers
> >
>
> There is fence_docker, you will need to configure docker on each
> physical host to accept remote connections from each cluster node. You
> will probably need one fencing agent for each physical host where docker
> is running and map cluster nodes (containers) to the correct agent (i.e.
> physical host).
>
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